The objective of this project is to devise more effective treatments for the blindness that develops in children after the removal of an infantile cataract. Infant monkeys are used to model this disorder because of the close similarities that have been demonstrated between the condition as it occurs naturally in humans and experimentally in our monkeys. The primary focus of our project during the past year has been to try to understand the neural basis for a defect in motion processing that is one of the prominent symptoms of children treated for this disorder. One primary unresolved question has to do with whether this motion processing deficit is due to amblyopia or whether it is due to the abnormal binocular interactions. These two factors cannot be isolated in human children because they are both present. We are using the animal model to disentangle these two factors by comparing conditions which lead to amblyopia (monocular occlusion) to conditions which disrupt bi nocularity but do not produce amblyopia (alternating occlusion). Monkeys in the alternating occlusion group have been reared during the past year and are currently undergoing behavioral testing. Monkeys in the continuous occlusion group are being reared this year for testing in subsequent years.